Electronic weft detector for looms



Oct. 21, 1947. v. F. SEPAVICH ETAL 2,429,529

ELECTRONIC WEFT DETECTOR FOR LOOMS' Filed July 23, 1945 3 Sheets-Sheet 1 IwvenTons VICTOR F SEPAVICH J'ouu CYMANOOG ATTORNLY Oct. 21, 1947. v. F. 'SYEPAVICH ETAL 2,429,529

ELECTRONIC WEFT DETECTOR FOR LOOMS Filed July 23, 1945 s Sheets-Sheet 2 FIB- E.

Iuvcnroas Anonwe Y Patented Oct. 21, 1947 ELECTRONIC WEFT DETECTOR FOB LOOMS 7 Victor F. Sepavlch and Jo ter, Mass., assignors to Loom Works, Worcester,

of Massachusetts hn C. Manoog, Worces- Crompton & Knowles Mass, a corporation Application July 23, 1945, Serial No. 606,600

32 Claims.

This application is a continuation in part of our copending application Serial No. 586,754 filed April 5, 1945.

This invention relates to improvements in weft detecting systems for looms, and it is the general object of the invention to provide electric means by which a contact occurring for a very brief interval of time at the shuttle when the latter is depleted of weft can be utilized to energize loom controlling electromagnetic device requiring a longer interval of time for its effective energization.

The usual type of electric weft detecting system employs a circuit in which the weft detector when giving indication of weft exhaustion is in series with an electromagnetic device. In such systems the circuit must remain closed at the detector for a length of time equal to that required for the full or effective energization of the electromagnetic device. The result of this relationship, especially at higher loom speeds, is that the weft detector must be set rearwardly a considerable distance to provide therequired time interval, but when thus set the detector is likely to cut fine weft, especially when a few strands only remain on the bobbin. The force of the blow which the bobbin strikes the detector causes the cutting, and this force can be reduced by moving the detector forwardly, but this entails a reduction in the length of the time during which contact exists with resultant insuflicient time for complete actuation of the electromagnetic device.

It is an important object of our present invention to introduce between the weft detector and the electromagnetic device electric circuit means potentially able to cause full energization of the device but prevented from doing so by a controller means which is altered when the detector closes contact. An electronic tube forms partof the electric circuit means and its grid is connected to the controller means and maintained by the latter at such potential as to prevent firing of the tube. When the detector indicates exhaustion the electric condition of the controller means is altered and acts to change the potential of the grid in such manner as will permit passage of current through the tube and energization of the device connected to the plate of the tube.

We have found that the grid controller means may conveniently comprise a small condenser and a high resistance connected in parallel across the grid and cathode of the electronic tube. Under normal conditions the condenser is kept charged by the diflerence of potential between the grid and cathode and maintains the potential of the grid below that of the cathode. When the detector indicates weft exhaustion the condenser is discharged, thereby raising the potential of the grid to permit current to flow 2 through the tube. Immediately after the detector contact is broken, recharging of the condenser starts and requires a sufllciently long time to hold or maintain the electronic tube in flring condition until the electromagnetic device has been fully energized. When the condenser is fully recharged the tube stops operation due to return of the grid to its normal potential, and the tube no longer causes energization of the electromagnetic device.

The electromagnetic device, which may be a relay or a solenoid, is preferably connected in parallel with a normally discharged condenser having a sufllcient capacity so that when discharging through the device the latter will be kept energized for a suiilciently long period to initiate a'change in loom operation. The condenser .is so connected to the electric circuit means that it is charged whenever the tube fires, and then discharge through the device after the detector contact is broken, and also when the potential of the tube plate becomes negative when alternating current is used. If desired a resistance may be introduced into the circuit including the condenser and electromagnetic device to prolong the time of flow of current from the condenser.

When the condenser is charged through a tube operating on ,an alternating current circuit the charging of the condenser will occur when the plate of the electronic tube is positive. When the current alternates and the plate becomes negative no current can pass through the tube, but the condenser, momentarily receiving no charge from the tube, can then discharge through the electromagnetic device. It is because of this'relationship that once energization of the device is started by the tube the energization will be continuous due to current flowing alternately first through the tube and then from the condenser.

The electromagnetic device always receives current flowing in the same direction from the tube and the condenser, a condition which might in time develop permanent magnetism of the device. It is another object of our invention to cause a small demagnetizing alternating current to flow through the electromagnetic device. This demagnetizing current is much smaller than the operating current derived from either the tube or the condenser and has no material effect in reducing the strength of the current supplied by the condenser. Since the tube is connected to the same source of current which supplies the alternating demagnetizing current, the latter can be passed through the device in such a direction as to aid the plate current when the latter flows.

In all types of weft detectors, particularly those employed on mu-tlicolor weft replenishing looms, some provision must be made to revent a false indication of weft exhaustion when the loom is 3 turned'over by hand and a depleted shuttle is at the detecting side of the loom.' This result is generally accomplished by some form of connection between the detector and shipper handle, or the weaver holds the detector forward in nondetecting position. We have found that with the type of detector set forth herein it is possible to set the detector so that it can indicate exhaustion only if the loom is operating-under power and will not indicate exhaustion if the loom is turned over by hand. This feature of our invention depends upon the fact that when the loom is operating the detector end of the lay tends to overthrow and atfront center move forwardly from the position which it occupies when the loom is turned over by hand. This slight amount of overthrow is suflicient to cause an operative contact between a depleted bobbin and the detector fingers.

With these and other objects in view which will appear as the description proceeds, our invention resides in the combination and arrangement of parts hereinafter described and set forth.

In the accompanying drawings, wherein two forms of the invention are shown,

Fig. 1 is a side elevation of a portion of a loom having the preferred form of weft detector system applied thereto,

Fig; 2 is a diagrammatic view of the circuits used in the preferred form of the invention,

Fig. 3 is a diagrammatic view of the circuits used in the modified form of the invention, and

Fig. 4 is a diagrammatic view showing how a characteristic of the lay motion when the loom runs under power can be utilized to cause closure of a detector contact long enough to operate the circuits shown in Figs. 2' and 3.

Referring to Fig. 1, we have shown a type of loom to which our invention can be conveniently applied. Such a loom is customarily employed for the weaving of fabrics made of fine wefts which might be damaged if the ordinary type of electric weft detector were employed. The loom frame In supports a top shaft H which by connectors I2 reciprocate the lay I! on which is mounted a shuttle box I4 for the shuttle S. The shuttle has a bobbin B therein which on alternate beats of the loom is presented to an electric weft detector designated generally at D. This detector may be of the type shown in Payne Patent No. 1,924,197 and has two prongs, electrodes or fingers l5 and i6, see Fig. 2, slidably mounted in a base I! made of insulating material. The fingers l5 and ii are electrically connected respectively to wires l8 and I! which lead respectively to binding posts 20 and 2| on the outside of a case or box K mounted conveniently on the loom frame. Under ordinary conditions when there is sufficient weft. for continued weaving on bobbin B the fingers or electrodes and I. are electrically disconnected or out of electrical contact with each other on detecting beats of the loom, but at weft exhaustion a ferrule 22 on the bobbin is uncovered and electrically connects the detector fingers or electrodes, thereby electrically connecting the binding posts and 2| through a contact which has negligible resistance.

The loom is provided with a magazine M which can be rocked by connections designated generally at 24 so that the bottom bobbin of either the front stack 25 or the rear stack 20 can be in transfer position under a transferrer arm 21. The mechanism 24 includes a hook ll controlled by a positioning lever 3| connected to shuttle boxes not shown at the opposite end of the loom by a flexible connector 82. Whenever there is a shift in the shuttle boxes lever II will rock so that the hook will either be in or out of the path of a pin 23. A lever 34 is rocked at two-pick intervals by a cam 25 on the bottom shaft 36. A normally stationary lever ll carries pin 23 and is pivoted on a stationary stud ll which also affords support for lever 34. The forward end of lever I0 is connected to an ascending rod 2 which when raised lifts a transferrer latch 43 into the path of a hunter 44 on the lay. The mechanism for determining when leverll shall be rocked is shown in the lower part of Fig. 1 and is designated generally at A. This mechanism includes a dog 45 on lever 34 and a lug 40 on lever 40 for engagement with the dog when the latter is deflected toward the lug. The means for deflecting the dog includes two indicator elements 41 and II which are under control of a solenoid or loom controlling coil 50 one at a time.

The matter thus far described is of common construction and for a further understanding of its operation reference may be had to Patents 2,054,192 and 2,138,974. During normal loom operation, solenoid 50 is deenergired and remains so until the detector establishes electrical contact with the ferrule 22, after which the solenoid is energized as will be described hereinafter to move one or the other of the indicator elements 41 or 48 into indicating position, thereby initiating a change in loom operation which subsequently causes dog 45 to engage lug 45. While one particular kind of loom has been shown, the different forms of the invention set forth hereinafter are not necessarily limited in their use to that type of loom.

Referring more particularly to Fig. 2 and the preferred form of the invention, the transformer '1 has a primary GI and a secondary 6| which supplies a current of low voltage, such as 6.3 volts, for the heater filament H of the cathode F of a gas filled thyratron electronic tube E, by means of wires 02 and 03. One side of primary is connected by wire 04 to a binding post which in turn is connected to post 2| and one of the power lines L. Wire 60 leads from post 20 to the control grid CG in tube E, and a high resistance R of the order of 10 megohms is connected across posts 20 and 2|. A small condenser C having a capacity of the order of 0.003 microfarad is connected across wire 66 and binding post 21 by wires 61 and GI.

The plate P of tube E is connected by wire 10 to one side of a relay coil or electromagnetic device 16 which may have a resistance of about 1500 ohms. When energized relay I6 closes a normally open switch 11. The other side of the relay is connected by wire 10 to post I! connected by wire I to secondary 60 and also connected to the other line wire L. A resistance R of the order of 30,000 ohms is connected to relay II by a wire ll forming a common connection between the resistance and relay, and the resistance R is also connected by wire 82 to post 08.

The screen grid 8G and one side of the cathode F are connected by wire 85 to one side of a restance R2 which may be of the order of 27,000 ohms, and the other side of the cathode is connected by wire 92 to one side of a resistance R3 of about 400 ohms the other side of which is connected to post I by wire 02. Resistance R3 acts as a cathode bias resistor, and wire 04 connects wires 02 and 03 so that the heater filament and cathode will be at the same potential. A resistance R4 of about 1000 ohms is in series with a normally discharged condenser having a capacity of about 20 microfarads. Resistance R4 is preferably variable to alter the time constant of the condenser-resistance unit C'-Rl. The various values of voltages, resistances, condensers, etc., given herein are those which have been used in a circuit which has operated successfully for several months, but the invention is not limited to these particular values, as will be pointed out hereinafter.

A loom control circuit shown at the right of Fig. 2 includes solenoid. 50 and switch 11, and when the latter is closed, current fiows as follows: secondary I00 of a second transformer T, wire Illl, binding post I02, wire I03, switch I1, wire I04, binding post I05, wire I06, solenoid 50, and wire I01 back to secondary I00. This circuit operates with about 12 volts potential and is closed to cause the solenoid to initiate a change in loom operation whenever switch 11 is closed.

The detector D and wires I8 and I9 leading from it to the binding posts 20 and 2I will have a smal capacitance and the condenser C is chosen to have a somewhat larger capacity. If wires I8 and I9 are quite long condenser C may need a larger capacity than that previously mentioned. Condenser C makes the detector circuit less sensitive to small change of capacity and resistance, and also acts to absorb any temporary surging which may develop in the circuits connected to it.

Under normal loom operating conditions the transformer T will be excited and will keep the heater H and cathode F at operating temperatures required for sufficient electron emission. The resistance R3 is of such value with respect to resistance R2 as to maintain the cathode permanently above the electric level of binding post 65 by a small voltage. It may be assumed for reasons which will-be set forth persently that condenser C has that end thereof connected to wire 66 negatively charged under normal conditions and therefore maintains the grid negative and at a potential below that of the cathode. This is the condition which prevents firing or operation of the tube and will continue so long as condenser C is charged.

When an empty bobbin is presented to the detector its ferrule 22 will establish electric contact with the detector fingers I5 and I6 which, by reason of wires I8 and I9, will short-circuit the resistance R and also discharge the condenser C. When the condenser C is discharged it loses much if not all of its effect on the control grid CG, so that the latter is no longer able to prevent firing of the tube, and the latter will be able to conduct current when the plate is positive and until condenser C again establishes normal electric condition at the grid.

During the time that the plate is positive and the control grid is still unable to block the passage of electrons to the plate, the following platerelay or operating circuit will be closed: plate P, wire 10, relay '16, wire 18, binding post 19, binding post 65, wire 92, resistance R3, wire 93, cathode F andacross the tube back to the plate. The relay is thus energized for what may be considered the first stage of its actuation continuing so long as the tube fires.

In Fig. 2 it will be noted that resistance R4 and condenser C are across wires 10 and 18. When the plate-relay or operating circuit is closed, therefore, current will also flow in the following condenser charging circuit, assuming the plate to be positive: wires 10 and H2, resistance 6 R4, wire II3, condenser C', wire I I4, and wire 18, thereby charging condenser C. When the polarity of plate P changes, current through the tube is interrupted and the condenser C causes current to flow in the following condenser discharge circuit: condenser C', wire II3, resistance R4, wire II2, wire 10, relay 16, wire 18, and wire III back to condenser C. Current will flow in this circuit while the tube plate is negative, and if when the plate is again positive the grid permits the tube to operate, the condenser C will receive another charge and the relay will be energized from the source of electric power. So long as the grid permits operation of the tube the relay will be energized alternately first from the tube and then from the condenser C, and continuous current will flow through the relay. If the grid prevents tube operation when the plate next becomes positive after charging condenser C, the latter, by reason of its capacity, will be able to continue energization of relay [6 until the solenoid is effectively energized,

As soon as the ferrule 22 moves away from the detector fingers I5 and I6 after indication of weft exhaustion has been given by closure of the detector contact, charging of the condenser C will start. It will be noted that the control grid CG is connected to the binding post 65 through wire 66, resistance R and binding post 2I, and that the cathode is at a potential above the binding post 65, hence there exists a potential drop from the cathode to the grid which causes current to fiow in the following circuit, post 55, wire 92, resistance R3, wire 93, cathode F, electronic stream across to control grid CG, wire 66, resistance R, binding post 2| and back to binding post 65. The direction of electron flow in this circuit is from the control grid to the resistance R, and since the condenser C is in parallel with the resistance R by reason of the wires 61 and 68, the electrons flowing to the left in wire 66 as viewed in Fig. 2 will accumulate on that part of the condenser C connected to wire 66. There is a resultant negative potential developed in the condenser due to accumulation of electrons, and since the negative part of the condenser is connected to the grid, the potential of the latter is determined by the condenser. As the condenser continues to be charged it becomes more and more negative and therefore effects a progressively increasing negativity of the control grid CG. The latter is in this way eventually restored to its normal negative relationship with respect to the cathode and the tube then ceases to fire.

The time interval required for recharging of condenser C has an important bearing on the successful operation of the plate-relay or operating circuit. This interval should be somewhat in excess of the length of a single alternation of the alternating current. The reason for this will be apparent if it be assumed that the detector contact should be broken at the beginning of a negative alternation. At such a time the plate P will be negative and the tube cannot fire, and if theccndenser C should become completely recharged during the time of the negative alternation the grid CG would again return to its normal condition of restraining firing of the tube before the plate became positive. the condenser C and the resistance R 50 that the time of charging the condenser will last longer than the negative alternation, time will be allowed for the plate to become positive before the condenser has made the control grid suificiently negative to stop operation of the tube.

By choosing dient across the cathode and grid will cause flow of a small current in wire 60 away from the grid, as already described. At the next alternation post 19 will be positive and current will flow from it over wires I8 and 80 through resistance R2 and wire 85 to the cathode, at which point the current is offered two paths for its return to the now negative post 05, one of these path being through the resistance R3 and the other being along wire 66, again in a direction away from the control grid. It will thus be seen thatduring successive alternations the condenser C is sub- Ject to charging in the same direction and it is for thi reason that its charge can accumulate to a point where it will make the grid negative and stop firing the tube.

It will be noted in Fig. 2 that resistance R and relay I are permanently in series across the primary of the transformer T and are included in the following demagnetizing circuit: binding post 65, wire 82, resistance R, wire II. relay I0, wire I8, and back to binding post 10. A very small alternating current is therefore always moving in this last named circuit to eflect a sufficient reversal of the magnetism of relay I6 to prevent the latter from becoming permanently magnetized. In this way proper conditions for closure of switch 11 are maintained in the relay over a long period of time. Post is common to both the plate and demagnetizing circuits so that when a current is flowing from the plate down through the relay, the demagnetizing current is also flowing down. The demagnetizing current therefore does not oppose but helps the plate current to actuate the relay. The demagnetizing current is too small to operate the relay when acting alone, or materially reduce the current discharged from the condenser C through the relay.

The box or casing K already mentioned contains many of the parts of the circuitsshown in Fig. 2, all in fact except the detector and the solenoid and their lead wires.

In the foregoing we have given certain specific values for the resistance R and for the condensers C and C, but we do not wish to be limited to these values inasmuch as wehave found that a considerable variation can be made in certainv of them. Thus, if the resistance R be 20 megohms condenser C can have a capacity as low as .001

microfarad, and if 'R be either five or ten megohms, the condenser C can have a capacity ranging from .003 to .25 microfarad. If resistance R is 2 megohms the range of the condenser C can be from .01 to .25 microfarad, but if resistance R is only one megohm the range of variation for the condenser C is narrowed, the lower limit being .01 and the upper limit being .10 microiarad. These values are approximate, since our tests 'were made with commercially available resistincreased, the condenser C' can be eliminated, indicating that condenser C has the effect of holding the grid at such a potential as will permit continued firing or operation of the tube beyond the time of contact of the detector with the bobbin. The condenser C, however, as already stated, should be larger than the capacity of the detector circuit, and its value is more critical than that of condenser C. While the latter can be smaller than 10 or 20 microfarads, and can in some instances be eliminated, we prefer, nevertheless to use the larger sizes mentioned.

In the modification shown in Fig. 3 resistances are shown connected to the control grid and the detector in such a way that when the detector closes contact the control grid voltage will be made less n gative or actually become positive with respect to the cathode to permit the tube to fire or operate. In this form of the invention the resistance R5 is preferably somewhat greater in ohmic value than the resistance R8, although this is not an essential relationship- A small con- III) denser C3 similar to condenser C is connected across resistance R5.

Normally, conditions with respect to resistance R5 and condenser Clare as described in the preferred form of the invention. Wire I35 connects the grid CG to the upper parts of resistance R! and condenser C3, and the latter holds the grid negative with respect to the cathode, When contact is closed at the detector the following circult is closed: post 65, post 2 I, resistance R5, wire I9, prong I6, ferrule 22, prong I5, wire I0, resistance R0, wire I36, wire III, relay I6, wire I0, and post 10. Except for the slight and negligible voltage drop across the relay, the full drop of voltage of the main line will be ,across resistances R5 and R0 with the grid connected at a point between these two resistances. The voltage drops will be proportional to the resistances, and resistance R5 is high enough to make the grid positive relatively to the cathode, and the tube will fire, At the same time, condenser C3 discharges through the detector and resistance R0, and maintains the grid positive until recharged.

It may be desirable at times to connect the detector to the solenoid circuit without using the electronic circuits shown in Fig. 2, in which case wires I20 and I2I can be used as indicated by dotted lines in Fig. 2. Wire I20 can be used to connect posts 20 and I02, while wire I2I in a similar manner can connect posts H and I05. These two wires, which may be kept with the equipment as readily attachable connectors, will not ordinarily be used, but if a loom to which the detector is applied happens to be weaving a fabric in which the weft is coarse the electronic circuits can be bypassed by these wires I20 and HI with suitable adjustment of the detector. or the wires can be used if temporary diiilculty develops in the electronic circuits.

Fig, 4 sets forth diagrammatically the manner in which an inherent property in the motion of the lay under power can be utilized to close the detector contact. The loom has two driving connectors I2 which are attached to the lay II at points I26 spaced from the ends of the lay. The shuttle boxes ordinarily extend beyond these connectors with respect to the center of the loom. In Fi 4 the dotted line I21 indicates that the lay is straight, the condition existing when the loom is turned over by hand and there is no momentum of the shuttle boxes to alter the shape of the lay. The solid line I20 indicates diagrammatically the contour of the lay when the loom is operating under power. That end of line I28 extending beyond the right connector 12 will at front center assume a position in front of the corresponding part of the dotted line I21 due primarily to the weight of the shuttle box which holds the shuttle containing the weft which is being detected. In Fig. 4 the bobbin ferrule22 is indicated in full lines in the position it will occupy when the loom' is operating under power, and when in this position it can contact the detector fingers l5 and I6. When the loom is be ing turned over by hand the bobbin ferrule will occupy the position 22 at front center and will not be able to engage the fingers l5 and I6, Because ofthis relationship no provision is needed to disconnect the detector system in order to prevent false indication when the loom is turned over byhand. With the usual type of detector system some provision must be made to prevent such a false indication if the weaver should turn the loom to front center with a depleted bobbin in detecting position.

From the foregoing it will be seen that we have.

provided a weft detecting system for a loom possessing exceptional sensitivity and so constructed that a very brief momentary contact of the detector prongs or fingers with the bobbin ferrule causes actuationof the loom controlling electromagnetic device. This result is attained by a grid controller means the normal action of which is to enable the grid to prevent firing of the tube, but when the detector contacts the empty bobbin the controller means is altered and the grid is changed in such manner as to permit current to flow through the tube and the electromagnetic deivce. Thecondenser C is normally charged to hold the grid negative relatively to the cathode, but when this condenser is discharged by the detector, there ensues a recharging period during which the grid is held at a raised potential long enough to permit firing of the tube E until the condenser C is charged. Also, the latter condenser discharges through the relay to prolong the energization started when the tube fires. Condenser C acts alternately with the tube to cause continuous flow of current through the relay during th period the condensenC is recharging. The demagnetizing feature prevents permanent magnetization of the relay. Furthermore, the very brief contact at the detector permits us to take advantage of the overthrow of the lay when the loom is operating to close a contact which cannot be closed when the loom is turned over by hand. The necessary duration of the detector contact is limited only by the time required to discharge condenser C, and'since this discharge can be effected in a very brief interval, only the barest detector contact is needed. We believe the condenser C acts in a. unique manner in controlling the grid CG, and so far as it is concerned, the detector D may beconsidered a signal means which effects a change in the normal condition of electrodes l5 and I6 whenever loom conditions require energization of a relay or solenoid corresponding to the signal means.

Having thus described our invention it will be seen that changes and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the invention and we do not wish to be limited to the details herein disclosed, but what we claim is:

1. In an electric weft detecting system for a 100m having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, the loom having a normally idle electromagnetic device which when energized initiates a change in loom operation, an electronic tube having a control grid therein, a source of electric power, operating circuit means including said device, tube and source, grid control means connected to the grid and normally operative to cause said grid to prevent flow of current through the tube and thereby maintain the perating circuit means inactive, and connections between said electrodes and grid control means operative when the electrodes are electrically connected to change the electric condition of said grid control means and cause the latter to alter the potential of said grid to permit current to flow through said tube, whereupon said operating circuit means energizes said device.

2. in an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, a source of electric power, a normal- 1y idle electromagnetic device which when energized initiates a change in loom operation, an electronic tube including a control grid, operating circuit means including said device, source and said tube, electric means connected to the grid and normally operative to maintain said grid at such electric potential as will prevent flow of current through said tube and thereby maintain said operating circuit means open, and connections between said electrodes and said grid control means effective when said electrodes are electrically connected to cause the grid control means to alter the electric potential of the grid in such manner as to permit current to flow through said tube and said operating circuit means for the purpose of energizing said device by electric power derived from said source.

3. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, a source of electric power, a normally idle electromagnetic device which when energized initiates a change in loom operation, an

electronic tube having a control grid therein, grid control means connected to the grid and normally maintaining said grid at an electric potential which prevents flow of current through the tube,

operating circuit means including said source,

tube and device normally open due to the normal condition of the grid but effective when current mit current to flow through said tube, whereupon said operating circuit means energizes said device. l

4. In an electric weft detecting system for a I loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, a source of electric power, a normally idle electromagnetic dew'ce which when energized initiates a change in loom operation, an eletronic tube including a grid, electric circuit means including said tube, source and device and efffective when current can pass through said tube to cause the source to energize the device, grid control means connected to the grid and normally effective to maintain said grid in such electric condition as to prevent current from flowing through the tube, and connections between the grid control means and said electrodes effective when the latter are electrically connected to alter said grid control means and the potential of said grid in such manner as will permit current to flow through said tube.

5. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, a source of electric power, a normally idle electromagnetic device which when energized initiates a change in loom operation, an electronic tube including a control grid, said tube being electrically connected to the source and device and the latter being connected to said source so that the latter will energize the device when current can pass through the tube, grid control means connected to the grid and including a normally charged condenser, said grid control means normally effective to maintain said grid in such electric condition as will prevent current from flowing through said tube, and connections between said grid control means and said electrode effective when the latter are electrically connected to discharge said condenser and cause said grid control means to alter the electric condition of the grid in such manner as will permit current to flow through said tube.

6. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, a source of electric power, a normally idle electromagnetic device which when energized initiates a change in loom operation, an electronic tube having a control grid therein, operating circuit means including said source, tube and device effective when current is able to pass through the tube to energize the device by electric power derived from said source, grid control means connected to the grid and including a condenser and a resistance connected in parallel with each other, and connections between said g id control means and said electrodes effective when the latter are electrically connected to discharge said condenser and short circuit said resistance and cause the grid control means to alter the electric condition of the grid in such manner as will permit current to flow through said tube.

7. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, a source of electric power, a normally idle electromagnetic device which when energized initiates a change in loom operation, an electronic tube having a cathode and a control grid, operating circuit means including said source, tube and device eifectiverwhen current is able to pass through said tube to energize said device by power derived from said source, said operating circuit means connecting one side of said source to said cathode, grid control means connected to the grid and also to said one side of said source and normally effective to maintain said grid in such electric condition as will prevent curreni: from flowing through said tube, and means eifective when said electrodes are electrically connected to alter said grid control means and thereby alter the electric condition of said grid in such manner as will permit current to flow through said operating circuit means.

8. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion; a source of electric power, a normally idle eelctromagnetic device which when energized initiates a change in loom operation, an electronic tube having a cathode and control grid therein, operating circuit means including said source, tube and device and effective to energize the latter when current is able to pass through said tube, said operating circuit means connecting the cathode to one side of said source, grid control means including a condenser connected to said grid and to said one side of the source and normally eifective to maintain said grid in such electric condition as will prevent current from flowing through said tube, and means effective when said electrodes are electrically connected to discharge said condenser and alter the grid control means in such a manner that the electric condition of the grid is changed to permit current to flow through said tube and electric circuit means.

9. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but electrically connected when a weft detector indicates weft exhaustion, a source of electric power, a normally idle electromagnetic device which when energized initiates a change in loom operation, an electronic tube including a cathode and control grid, operating circuit mean including said source, tube and device effective to energize the latter when current is able to flow through said tube, said operating circuit means connecting said cathode to one side of said source, grid control means including a condenser and a resistance in parallel with each other and connected to the grid and to said one side of the source, said grid control means normally effective to maintain the grid in such electric condition as will prevent flow of current through the tube, and means eifective when the electrodes are electrically connected to discharge said condenser and change the electric condition thereof and also the electric condition of the grid in such manner as will permit current to ilow through the tube.

10. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but which upon indication of weft exhaustion by a weft detector are electrically connected for a brief interval, the loom having an electromagnetic device which when energized for a period of time longer than said brie! interval initiates a change in loom operation, a source of alternating current, an electronic tube having a plate connected to said source and being alternately positive and negative, current being capable of passing through said tube only when the plate is positive, operating circuit means including said source. tube and device effective when said plate is positive and current is able to pass through said tube to energize the device by electric power derived from said source,

grid means in the tube normally effective to prevent flow of current through the tube when the plate is positive and the electrodes are electrically disconnected, and electric control means for the rid connected to said grid and electrodes and effective if said electrodes are electrically connected when the plate is negative to maintain said grid in such condition and for such a length of time as to permit current to flow through said tube 3?: said period to eifect energization of said 11. In an electric weft detecting system for a loom having two electrodes normally electrically disconnected from each other but which upon indication of weft exhaustion by a weft detector are electrically connected for a brief interval, the

loom having an electromagnetic device which when energized for a period of time longer than said brief interval initiates a change in loom operation, a source of alternating current, an electronic tube having a plate connected to said source and being alternately positive and negative, current being capable of passing through said tube only when the plate is positive, operating circuit means including said source, tube and device effective when said plate is positive and current is able to pass through said tube to energize the device by electric power derived from said source, grid means in the tube normally effective to prevent flow of current through the tube when the plate is positive and the electrodes are electrically disconnected, and electric control means for the grid including a normally charged electric condenser which is discharged when the electrodes are electrically connected and effective during said period of time to permit current to flow through I said tube to effect energization of said device.

12. In an electric weft detecting system for a loom having a source of alternating current, an electromagnetic device which when effectively energized initiates a change in loom operation, an electric resistance, circuit means permanently connecting said device and resistance across the course of alternating current, said resistance and electromagnetic device having a combined resistance which permits flow through said device of a small demagnetizing current ineffective to energize the device, and electric means operative upon indication of weft exhaustion in the detecting system to cause current of sufilcient strength to energize the device effectively to now through said device.

13. In an electric weft detecting system for a loom having a source of alternating current supply, an electromagnetic device which when effectively energized initiates a change in loom operation, an electric resistance, electric .means permanently connecting the resistance and electromagnetic device in series across said source of supply, the combined resistances of said resistance and device being such as to maintain a demagnetizing current in the device insufilcient to energize the latter efiectively, and electric circuit means operative upon indication of weft exhaustion to cause current from said source to flow through said device and bypass said resistance for the purpose of producing a current in said device sufliciently large to cause effective energization thereof.

14. In an electric weft detecting system for a loom having a source of alternating current supply, an electromagnetic device which when effectively energized initiates a change in loom operation, an electric resistance, electric means permanently connecting the resistance and electromagnetic device in series across said source of supply, the combined resistances of said resistance and device being such as to maintain a demagnetizing current in the device insufficient to energize the latter effectively, and electric circuit means operative upon indication of weft exhaustion to cause a larger operating current derived from said source and from alternations thereof of one polarity only to flow through said device and bypass said resistance for the purpose of causing efiective energization of said device.

15. In an electric weft detecting system for a loom having a source of alternating current sup ply, an electromagnetic device which when efiectively energized initiates a change in loom operation, an electric resistance, electric means permanently connecting the resistance and electromagnetic device in series across said source of supply, the combined resistances of said resistance and device being such as to maintain a demagnetizing current in the device insufiicient to energize the latter efiectively, and electric circuit means operative upon indication of weft exhaustion to cause a larger operating current derived from said source and from alternations thereof of one polarity only to flow through said device and bypass said resistance for the purpose of causing efl'ective energization of said device, said electric circuit means being so arranged that the demagnetizing and operating currents are always of the same polarity.

16. In an electric weft detecting system having an electric weft detector and a source of alternating current supply, an electromagnetic device which when efiectively energized initiates a change in loom operation, a resistance, a common connection between said device and resistance, electric circuit means connecting one side of said source to that side of the resistance opposite said common connection and connecting the other side of said source to that side or the device opposite the common connection to cause a small demagnetizing current incapable of effectively energizing the device to flow through the latter to demagnetize the same, and electric circuit means controlled by the detector and operative when the latter indicates weft exhaustion to connectsaid one-side of the source to said common connection to cause current of suflicient strength to cause effective energization of said device to flow through said device without flowing through said resistance( 17. Inan electric weft detecting systemfor a loom having a weft detector which electrically connects two normally disconnected electrodes for a given interval of time when indicating weft exhaustion, the loom having an electromagnetic device which when energized by passage of electric current therethrough for a period of time longer than said interval initiates a change in loom operation, a source of electric power, and electric circuit means including an electronic tube having a control grid connected to a charged condenser and normally preventing energization of said device by said source and including electric means efl'ective when said electrodes are electrically connected for said interval to discharge said condenser and alter said grid, saidlcircuit means thereupon causing electric current to flow through said device for said period.

18. In a loom having an electromagnetic device which when energized controls a loom part, the loom having also signal means corresponding to said loom part and electrically connecting normally disconnected electrodes when the condition of the loom requires energization of said device,,

than said one side, a control means for the grid including a resistance and a condenser both connected to said one side of the source and both 15 connected to said grid, the condenser being normally charged and causing a normal condition of the grid which prevents passage of electric current through said tube, and means causing discharge of said condenser when said signal electrodes are electrically connected, said grid there-T upon having an abnormal condition due to discharge of the'condenser and permitting electric current to pass through said tube, and said condenser thereafter being recharged subsequent to return of the electrodes to their normal disconnected condition by power derived from said source and passing through said cathode and grid to restore the latter to normal condition.

19. In a loom having an electromagnetic device which when energized controls a loom part, the loom having also signal means corresponding to said loom part and electrically connecting normally disconnected electrodes when the condition of the loom requires energization of said device, a source of electric power, an electronic tube connected to said source and device in such manner that when current can pass through the tube the device will be energized by power derived from said source, a control grid in the tube, a condenser connected to the grid and normally charged in such manner as to enable the grid to prevent passage of electric current through the tube, means effective upon electric connection of said electrodes to discharge said condenser, whereupon the grid permits passage of electric current through the tube, and means connected to said source operative subsequent to disconnection of said electrodes to recharge said condenser.

20. In a loom having an electromagnetic device which when energized controls a loom part, the loom having also signal means corresponding to said loom part and electrically connecting normally disconnected electrodes when the condition of the loom requires energization of said device, a source of electric power, an electronic tube connected to said source and device in such manner that when current can pass through the tube the device will be energized by power derived from said source, a control grid in the tube, grid control means connected to the grid and includin a normally charged condenser, said condenser normally effective to maintain said grid in such electric condition as to prevent passage of current through said tube, and means to discharge the condenser when said electrodes are electrically connected, discharge of the condenser changing the electric condition of the grid to permit passage of electric current through the tube.

21. In weft detecting means for a loom having a weft detector which gives an indication during a weft detecting operation of the loom upon exhaustion of weft, the loom having operating electric circuit means including an electronic tube and an electromagnetic device which is energized to initiate a changein loom operation when current can flow through the tube, a control grid in the tube, grid control circuit means including a normally charged condenser which due to the charge thereof maintains the grid in such electric condition as to prevent flow of current through the tube, and electric means effective when the weft detector gives an indication to discharge the condenser and thereupon alter the condition of the potential of the grid to permit current to flow through the tube, said grid control circuit means thereafter effecting recharging of the condenser and the latter maintaining the potential of the grid at said altered condition until the condenser is recharged.

22. In an electric weft detecting system for a loom, a weft detector which changes the electric contact relation of two electrodes for a brief interval when indicating weft exhaustion, a source of electric power, an electromagnetic device which when effectively energized initiates a change in loom operation, a normally discharged electric condenser connected in parallel with said device, and electric means effective when said detector changes the electric contact relation of said electrodes to cause said source of electric power to energize said device and also charge said condenser, the latter being operative subsequent to said interval to discharge through said device to cause effective energization thereof.

23. In an electric weft detecting system for a loom having an electric weft detector to indicate weft exhaustion during a momentary period, the loom having an electromagnetic device which when effectively energized initiates a change in loom operation, a normally discharged condenser electrically connected to said device and normally incapable of eflectively energizing said device, electric means potentially capable of charging the condenser but normally ineffective to do so, and means causing said-electric means to charge said condenser whenthe detector indicates weft exhaustion during said momentary period, said condenser causing effective energization of said device subsequent to said momentary period.

24. In an electric weft detecting system for a loom having an electric weft detector which indicates weft exhaustion during a momentary period. the loom having an electromagnetic device which when effectively energized initiates a change in loom operation, a normally discharged condenser electrically connected in parallel with said device and normally incapable of effectively energizing said device, electric means controlled by said detector and potentially capable of charging the condenser and simultaneously energizing said device effectively but normally incapable of doing so, and means operating when the detector indicates weft exhaustion to cause said electric means to charge said condenser and eil'ectively energize said device during said momentary period, said condenser continuing the eii'cctive energization of said device subsequent to said momentary period.

25. In an electric weft detecting system for a loom including an electric weft detector and an electromagnetic device which when effectively energized initiates a change in loom operation, a normally discharged condenser, a resistance, electric circuit means connecting said device, condenser and resistance in series, and electric means controlled by the detector and effective when the latter indicates weft exhaustion to charge said condenser, saidv condenser thereafter discharging through the resistance and device to cause effective energization of the latter.

26. In an electric weft detecting system for a loom having an electric weft detector which electrically connects two electrodes during a momentary period when indicating weft exhaustion, the loom having a source of electric power, an electromagnetic device which when eifectively energized initiates a change in loom operation, a condenser, a resistance, circuit means connecting said device, condenser and resistance in series, and electric means controlled by the detector and operative when the latter connects said electrodes to connect said source to said condenser to charge the 17 latter, said condenser thereafter dischargins through said device to nergize the. lattereifectively subsequent to said momentary period.

27. In an electric weft detecting system for a loom having an electric detector provided with two electrodes normally spaced but brought into electric contact when the detector indicates weft exhaustion and wherein a source of electric power has one side thereof connected to one side of an electromagnetic device which when effectively energized initiates a change in loom operation, an electronic tube having a cathode connected to the other side of said source and hav-' ing a plate connectedto the other side of said electromagnetic device and having a control 30. In an electric weft detecting system for a loom having an electric weft detector, the loom having an electromagnetic device which when energized initiates a change in loom operation, and two electric means for energizing said electromagnetic device in two successive stages, the

first of said means including an electronic cirgrid, electric means connected to the source and said plate and said one side of said source, electron flow through said tube effecting energiz'ation of said electromagnetic device and effecting storage of a charge of electricityin said condenser, and the latter upon stoppage of electron flow through the tube discharging through said electromagnetic device to continue the effective energization of said device.

28. In an electric weft detecting system for a loom having a detector provided with two electrodes normally spaced but brought into electric contact when the detector indicates weft exhaustion, a source of electric power, a normally idle electromagnetic device which when effectively energized initiates a change in loom operation, a normally idle electronic tube, a normally discharged condenser, means causing electric cur rent toflow through the tube when the electrodes are in electric contact, and circuit means by which said electromagnetic device is effectively energized and said condenser is charged by electric power derived from said source when current flows through said tube, said circuit means having provision by which said condenser discharges through said device to continue effective energizatlon of said device after current ceases to flow through said tube.

29. In an electric weftdetecting system for a loom having an electric weft detector provided with two electrodes normally spaced but brought into electric contact when the detector indicates weft exhaustion, the loom having an electromagnetic device which when effectively energized initiates a change in loom operation, a normally discharged condenser in parallel with said electromagnetlc device, a source of electric power, normally idle electronic circuit means including said sourceof electric power and an electronic tube for said condenser and electromagnetic device, and means controlled by the weft detector and effective when the electrodes are in electric contact to cause current to flow through said tube and in said electronic circuit means to charge the condenser and effectively energize said electromagnetic device, said circuit means having provision by which the condenser discharges through said device to continue effective cult including said device and called into action by the detector when the latter indicates weft exhaustion to energize said device during the first stage, and the second means including a condenser which is charged when current flows in the electronic circuit and discharges upon opening of the electronic clrcuit'to energize said de vice effectively during thesecond stage.

31. In an electric weft detecting system for a loorn having a source of alternating current supply, an electromagnetic'device which when effectively energized initiates a change in loom operation, an electric resistance, electric means permently connecting the resistance and electromagnetic device in series across said source of supply, the combined resistance or said resistance anddevice being such as to maintain a demagnetizing current in the device insufflcient to energize the latter effectively, and electric circult means operative upon indication of weft I exhaustion to connect one side of said source to a point between the resistance and device to cause a current from said source to now through said device and bypass said resistance for the purpose of producing a current in said device sufllci'ently large to cause effective energization thereof.

' 32. In an electric weft detecting system for a loom having a weft detector and a source of alternating current supply. an electromagnetic device which when effectively energized initiates a change lnrloom operation, an electric resistance, electric circuit means connecting one side of said source to said resistance and the other side of said source to said device and*connecting said resistance and said device in series, and other electric circuit means controlled by the weft detector and effective when the latter indicates weft exhaustion to connect said one side of the source to said electromagnetic device to cause a current of sufficient strength to cause efiective energization of said device to flow through said so device without flowing through said resistance.

VICTOR- F. SEPAVICH. JOHN C. MANOOG,

anr'nnnncns crrnn The following references are of record in the file of this patent:

current flow through said tube.

UNITED STATES PATENTS Number Name Date 2,026,148 Turner Dec. 31, 1935 2,065,730 Payne Dec. 29, 1936 2,146,011 Young Feb. 7, 1939 2,228,225 Brown Jan. 7, 1941 2,233,483 Metcali' Mar. 4, 1941 2,330,212 Hayes Sept. 28, 1943 2,346,240 Thomas -e-.. Apr. 11, 1944 2,377,102 Payne May 29, 1945 FOREIGN PATENTS Number Country Date Great Britain Oct. 19, 1933 

